In recent years, compactness, high output, and high quality have been required in rotary electric machines that are used as electric motors or generators. In high-output rotary electric machines of this kind, since high voltages are applied, electric potential differences that arise between coils that are mounted into an armature core have increased, and it has become necessary to have electrical insulation distances that can bear them. However, if electrical insulation distances are increased, then heights of coil ends are increased proportionately, enlarging the rotary electric machine overall.
In consideration of such conditions, conventional rotary electric machines have been proposed that achieve reductions in size by making a cross-sectional shape of rectilinear portions of coils that are inserted into slots into a rectangular shape to increase space factor and enable increases in output, while also making a cross-sectional shape of coil end portions that links together the rectilinear portions into a circular shape to suppress interference among the coil end portions and reduce coil end height (see Patent Literature 1, for example).